MAMARONECK, N.Y. -- A Mamaroneck mother who was charged with killing her 4-year-old son pleaded not guilty to second-degree murder on Friday, Aug. 15, according to LoHud.com.

Manuela Maria Morgado allegedly tried to kill Jason "Jake" Reish by drugging him, then suffocating him with helium. Morgado then allegedly gave up on the helium and smothered her son with a pillow, LoHud.com reported.

Authorities found Morgado with her son's corpse in her arms and a suicide note, LoHud.com said.